Development of Porous Photopolymer Resin-SWCNT Produced by Digital Light Processing Technology Using for Bone Femur Application.

BACKGROUND: Although bone tissue has the unique characteristic of self-repair in fractures, bone grafting is needed in some situations. The synthetic substances that are used in such situations should bond to the porous bones, be biocompatible and biodegradable, and do not stimulate the immune responses. Biomaterial engineering is the science of finding and designing novel products. In principle, the most suitable biodegradable matrix should have adequate compressive strength of more than two megapascals. At this degradation rate, the matrix can eventually be replaced by the newly formed bone, and the osteoprogenitor cells migrate into the scaffold. This study aimed to evaluate the fabrication of a scaffold made of polymer-ceramic nanomaterials with controlled porosity resembling that of spongy bone tissue. METHODS: A compound of resin polymer, single-walled carbon nanotube (SWCNT) as reinforcement, and hydroxyapatite (HA) were dissolved using an ultrasonic and magnetic stirrer. A bio-nano-composite scaffold model was designed in the SolidWorks software and built using the digital light processing (DLP) method. Polymer-HA scaffolds with the solvent system were prepared with similar porosity to that of human bones. RESULTS: HA-polymer scaffolds had a random irregular microstructure with homogenizing porous architecture. The SWCNT improved the mechanical properties of the sample from 25 MPa to 36 MPa besides having a proper porosity value near 55%, which can enhance the transformation and absorption of protein in human bone. CONCLUSION: The combined bio-nanocomposite had a suitable porous structure with acceptable strength that allowed it to be used as a bone substitute in orthopedic surgery.

Improvement in osseointegration of tricalcium phosphate-zircon for orthopedic applications: an in vitro and in vivo evaluation.

Similar to metallic implant, using the compact bio-nanocomposite can provide a suitable strength due to its high stiffness and providing sufficient adhesion between bone and orthopedic implant. Therefore, using zirconia-reinforced calcium phosphate composites with new generation of calcium silicate composites was considered in this study. Additionally, investigation of microstructure, apatite formation, and mechanical characteristic of synthetic compact bio-nanocomposite bones was performed. Desired biodegradation, optimal bioactivity, and dissolution of tricalcium phosphate (TCP) were controlled to optimize its mechanical properties. The purpose of this study was to prepare the nanostructured TCP-wollastonite-zirconia (TCP-WS-Zr) using the space holder (SH) technique. The X-ray diffraction technique (XRD) was used to confirm the existence of favorable phases in the composite's structure. Additionally, the effects of calcination temperature on the fuzzy composition, grain size, powder crystallinity, and final coatings were investigated. Furthermore, the Fourier-transform infrared spectroscopy (FTIR) was used for fundamental analysis of the resulting powder. In order to examine the shape and size of powder's particles, particle size analysis was performed. The morphology and microstructure of the sample's surface was studied by scanning electron microscopy (SEM), and to evaluate the dissolution rate, adaptive properties, and the comparison with the properties of single-phase TCP, the samples were immersed in physiological saline solution (0.9% sodium chloride) for 21 days. The results of in vivo evaluation illustrated an increase in the concentration of calcium ion release and proper osseointegration ratio, and the amount of calcium ion release in composite coatings was lower than that in TCP single phase. Nanostructured TCP-WS-Zr coatings reduced the duration of implant fixation next to the hardened tissue, and increased the bone regeneration due to its structure and dimensions of the nanometric phases of the forming phases. Finally, the animal evaluation shows that the novel bio-nanocomposite has increasing trend in healing of defected bone after 1 month.

A porous polymeric-hydroxyapatite scaffold used for femur fractures treatment: fabrication, analysis, and simulation.

BACKGROUND: One of the most common fractures in the skeleton happens in the femur. One of the important reasons for this fracture is because it is the longest bone in the body and osteoporosis affect this part a lot. The geometric complexity and anisotropy properties of this bone have received a lot of attention in the orthopedic field. METHODS: In this research, a femur designed using 3D printing machine using the middle part of the hip made of polylactic acid-hydroxyapatite (PLA-HA) nanocomposite containing 0, 5, 10, 15, and 25 wt% of ceramic nanoparticle. Three different types of loadings, including centralized loading, full-scale, and partially loaded, were applied to the designed femur bone. The finite element analysis was used to analyze biomechanical components. RESULTS: The results of the analysis showed that it is possible to use the porous scaffold model for replacement in the femur having proper strength and mechanical stability. Stress-strain analysis on femoral implant with biometric HA and PLA after modeling was performed using the finite element method under static conditions in Abaqus software. CONCLUSION: Three scaffold structures, i.e., mono-, hybrid, and zonal structures, that can be fabricated using current bioprinting techniques are also discussed with respect to scaffold design.